CA1191180A - Pushbutton switch, in particular key switch - Google Patents

Pushbutton switch, in particular key switch

Info

Publication number
CA1191180A
CA1191180A CA000413157A CA413157A CA1191180A CA 1191180 A CA1191180 A CA 1191180A CA 000413157 A CA000413157 A CA 000413157A CA 413157 A CA413157 A CA 413157A CA 1191180 A CA1191180 A CA 1191180A
Authority
CA
Canada
Prior art keywords
plunger
contact
axially
extending
switch
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA000413157A
Other languages
French (fr)
Inventor
Reinhard L. Fricke
Klaus Hinze
Manfred K.O. Huth
Kalus B. Wisskirchen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ITT Inc
Original Assignee
ITT Industries Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to DE3140199A priority Critical patent/DE3140199C2/de
Priority to DEP3140199.6 priority
Application filed by ITT Industries Inc filed Critical ITT Industries Inc
Application granted granted Critical
Publication of CA1191180A publication Critical patent/CA1191180A/en
Expired legal-status Critical Current

Links

Classifications

    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H13/00Switches having rectilinearly-movable operating part or parts adapted for pushing or pulling in one direction only, e.g. push-button switch
    • H01H13/02Details
    • H01H13/12Movable parts; Contacts mounted thereon
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00Contacts
    • H01H1/12Contacts characterised by the manner in which co-operating contacts engage
    • H01H1/14Contacts characterised by the manner in which co-operating contacts engage by abutting
    • H01H1/20Bridging contacts
    • H01H1/2025Bridging contacts comprising two-parallel bridges

Abstract

PUSHBUTTON SWITCH

Abstract Of The Disclosure:

A pushbutton switch is provided comprising a leaf spring with slotted leaf ends for forming a double contact and a fixed contact arranged transversely in relation thereto. The slotted spring ends, in the direction of the leaf spring axis, are pro-vided with groove-shaped stampings. This results in a point-shaped contact which migrates as a result of the bending of the leaf spring so that a high contact pressure is produced and a self-cleaning of the contacts is achieved.

Description

~9~
....

R~L.Ericke-K.Hinze~M.K.O.Huth-K.BOWisskirehen 2-10-1-3 Pushbutton switch, in particular key switeh The present invention relates to a puLshbutton switch, par-ticularly to a key switch, eomprising a switeh plunger ~apable of being displaeed in the axial direetion in op-position to the force of a compression or snap-aetion spring, whose end earries a eontaet spring with eontaet arms standing off on both sides, with the eontaet arms at least within the end part, by being slotted in the longitudinal direetion, being desic~ned as dual contaets whieh are capable of co-operating with fixed eontaets having a roller-like rounded eontaet path, arranged ver~
tically in relation to the slot direetion and, at least within the contact-ma~ing area, consist of a Elat ma-terial.

One sueh pushbutton (key) switch is known, ~or example, from the applieant's earlier DE-OS 2 942 720 ~W~Rosl-21).
In this conventional type of pushbutton swi~eh, the eon-tact spring is designed as a flat spxing ex.ending in one plane, and the contact surfaces are likewise of a plane design~ When completely applied, this results in a large-area eontact at the contact-making ~oint. This, however, effects a relatively small eontaet pressure which, especially in the case of pushbutton switches which are only supposed to have a small pushbutton pres-sure, is considered disadvantageous~ If the contactspxing eont'd.

or -the rixed contact, or both, however, for some reason or other, are not exactly assembled in the same plane, the edge of -the con-tact spring is positively connected to the contact path, with -this resulting in a rather high contact pressure and, -there-fore, in a very considerable wear, because -the edges are sharp.

Moreover, from DE-AS 1 003 318 it is already known with respect to a slide switch for very high actuating forces, serving as a limit swi-tch, to rivet contact rivets to the ends of -the contact spring.

In this swi-tch, the stationary opposite contacts are circularly arched inwardly, so that during the pressing and bending oE -the contact spring, the contact rivets are capable of sliding frictionally on the circular contact path. This is supposed -to result in a self-cleaning of the contacts during operation.

Furthermore, from the German ~tili-ty Model DE-GM 7 220 520, it is already known to design the contact areas of an isolating switch for use in telecommunication systems, in such a way by crossing beads -that a point-shaped contact results. By this it is intended to achieve a high contac-t pressure.

It is the object of the invention to achieve, with respect to a pushbu-tton swi-tch for a low pushbutton pressure, a self-cleaning, as well as to enable a high contact pressure.

According to the invention there is provided an electrical push-button switch comprising, in combination: a casing having an axis, axially extending wall por-tions, a base portion and at least two radially spaced stationary contacts rnounted to said base and extending axially upwardly; a rod-shaped switch plunger axially rnovable ln sa:Ld casing and having a pai.r o:E arms ex-tendinq in :radia].ly opposi-te directions frorn an axially in-termediate portion of said plunge:r; a leaf spring contac-t moun-ted at a cen-tral portion thereof to the axial]y inner end portion of sai.d plunger and extending outwardly in radial.ly opposite direc-tions there:Erom for engaging said stationary contacts when said plunger is moved toward said base; a compression spring extending through a trans-verse through bore in an intermediate portion of said plunger and respectively terminating in radially opposite groove portions of said wall portions of said casing, said compression spring resiliently urging said plunger away from said base, and, a cover enclosing the axially outer end portion oE said casing and having a central opening for receivi.ng said plunger and said cover having a pair of axially extending radiall.y opposite guide grooves :Eor receiving radially ou-ter ends of said arms for guiding and angular-ly orientatiny said plunger.

Further advantageous details of the invention will now be described hereinafter with reference to an example of embodiment shown in Figures 1 to 10 of the accompanying drawings, in which:
Figure 1 is the exploded view of the switch according to the invention, Figure 2 shows the employed switch plunger from below, Figure 3 shows -the switch plunger in a side view, Figure 4 shows part of the contacts of the switch on an enlarged scale, Figures 5 and 6 show the dual contact when looked at R.r,. Fr:iclce e~l aL. 2~:Ln 1--3 ln the clirection of the Flat spr:incJ, Fig~O 7 arlcl 8 show the contact according to Figs.
5 and 6 in a view stagcfered by 90 degrees, Ficl. 9 shows the flat spring ln a top view, Fig. 10 is a sectional view o F the contact spring taken on the line A-B oE Fig. g, Fig. 11 is a bottom view of the switch plun~er, and Fig. 12 is a side view of the swi~ch plunger of Fig. 11 shown in conjunction with a lea~-shaped contact spring.
The reference numeral 1 indicakes a cup-shaped and in th~ top vie~ preferably square-shaped casing mouldec1 from, Eor example, an elastically deformable insulating materi~l~
~t its diayonally oppositely arranged corners 2 and 3 there are provided plug-in 510 ts 4 arranged vertically in relation to the dia~onal line, in which one fixed contact S each is capahle of being plugged by means of its narrow tongues 6, and is capahle of being fixed there-in. The upper flat and widened portion 7 is provided with an upper roller-shaped, rouncled contact path 8.

At the bo~tom 9 of the casing 1 there are arranged four webs 10 projecting vertically in the upward direction, which serve the centering, ~he axially displaceable and rotatable bearing of a switch plunger 11 made of a suit-able plastics material. The latter has a disk shaped lower end 12 with a downwardly pro~ecting flap-shaped extension 13 (Figs. 11 and 12~. On to this extension 13 there is ~lipped a lancet-like, leaf-shaped contact spring 14 by means of a central recess 15 adapted to the ~ross~
section of the extension 13, and is fi~ed in its posi-tion by way of a mechanical, plastic and/or thermoplastic s ~

R.L.Fricke 2-10-1-3 deformation of the extension 13.

The outer edge 16 of the switch-plunger end 12 together with the inner surfaces 17 of the webs 10, forms a lower shaft bearing. The insertion depth of the switch plunger 11 is restricted by its supporting surface 18 and by lateral supporting means 19 at the bottom 9 of the cas-ing 1. The latter are so designed and arranged that the extension 13 of the switch plunger 11 is prevented from ~ouching the bottom 9, and that the contact spring 14 is capable of mo~ing between them.

In its lower third the switch plunger 11 is provided wi.th an opening 20 extending in the direction of the contact spring 14. Through this opening, a spiral spring 21 can be pushed, with the standing-off ends 22 thereof being bent downwardly upon insertion of the switch plunger 11 into the casing 1, for engaging into grooves 23 of the casing 1. These grooves 23 are provided for in the cor-ners 24 neighbouring the corners 2 and 3~ The bottom of these grooves is inclined from the outside towards the inside and extends slantingly in the upward direction~

Following the insertion of the switch plunger 11; the housing 1 is topped by a cover 25 preferably consisting of an elastica~ly deformable insulating material, with both parts being locked to one another with the aid of suitable snap-action elements 26, 27 and 28, 29 associa~
ted with one another. In so doing, the extensions 30 with their top parts extending from the outside towards the inside slantingly in the upward directio~, press upon the ends 22 of the spiral spring 21, thus clamping the latter cont'd.

R.L.Fricke 2~10-1-3 in the arched position. ~n this way there is achieved the desired snap action of the pushbutton switch or of the switch plunger 11 respectively. When at normal, the switch plunger 11 is pushed upwardly thus permitting it to meet with a collar 32 against the inside of the cover.

In the assembled state, the central shaft~shaped por-tion 33 of the switch plunger 11 together with a ring-shaped recess 34 in the cover 25, forms an upper bearing.

According to the invention, the contact arms 35 of the contact spring 14 as standing off on both sides from the mounting point (extension 13) are each provided with a longitudinal slot 36, so that per contact arm there is obtained a dual contact.

The contact area 37 of the contact spri.ng 14 may be pro-vided with a special contact layer. According to the invention, and by a stamping 38, it is provided with an arching extending i.n the slot direction, with the con-vex surface thereof, in the assembled state, lying op-posite the associated fixed contact 5. In this way it is accomplished that the fixed contact 5 may also be slanting in relation to the plane of the con-tact spring 14 and yet preventing any sharp lateral edge thereof from pressing upon the contact path 8 (Figs. 5 and 6).

The arrangement is made in such a way that the switch plunger 11 is capable of being actuated in the over-travel, i.e. that it, from the moment of contact making, is still capable of being further moved axially in the cont'd~

R.L.Fricke 2~10~ 3 downward direction. The overtravel is so large that the ends 39 of the contact arms 35, owing to the bending through of the contact spring 14, are capable of being deflected by about 10 to 35 % of the length of the free arm length 40 of the contact spring 14. Owing to the bending through of the contact spring 14, the point o contact P of the contact area 37 is displaced further ~owards the outside and, in addition thereto, the sup-porting point of the con-tact area 37 moves on the con-kact path 8 by the angle of contact ~ ~ By the arching of the con-tact areas 37 it is accomplished that through-out the entire contact path sec-tion which is swept over by the angle of contact ~ , there is achieved a point-shaped support. Accordillgly, in this way there i.s achieved a hi.gh con~.act pressure and, consequently, a lower transfer resistance throughou-t the entire contact area and, in addition thereto, a self-cleaniny of the contacts.

According to one preferred embodiment of the invention, the suppoxting surf2ce 18 of the switch plunger end 12 is arched in the direction of the bending through of the contact spring 14. Preferably, the arching has at least approximately such a shape as can be assumed by the con-tact spring 14 during its maximum bending through. The arching radius has about 1.2 to 2 times the size of one free contact axm length 40. Preferably, the length of the supporting surface in the direction of the con~
tact spring axis amounts to about 20 to 40 % of the length of the contact spring 14.

An appropriate further embodiment of the invention shows that the bearings of the s~itch plunger 11 in~
cont~d.

.L~ 3~) .L,.Fricke 2-10-1-3 side the casing 1 and inside the cover 25 are designed to have a circular cross-section, and that the exact angular position of the contact spring 14 is achieved by rela-tively long sliding fingers 41 extending in the same, preferably radial, direction as the contact arms ar-ranged above the contact spring 14. The ends 42 thereof each slide in a vertical guide groove 43 in the casing 1 or in one of the casing parts, in particular inside the cover 25. For achieving a maximum possible length of the sliding fingers 41, the guide grooves 43 are pro-vided for in the corners 44, 45 of the cover 25 cor-responding to the diagonally opposite corners 2, 3 of the casing 1. By this measure there is achieved a hi.gh angu~
lar accuracy by maintaining the usual manufacturing tol-erances of the plastics mo-1ldings. If, for example, the switch plunger ll itself were to be designed to have a square shape for example, then certain minimum sp~cings or minimum tolerances would have to be adhered to in order to safeguard a smooth running and to avoid a tilting or twisting. When consi.dering the small size of the switches for the use with keyboards for co~pu-ters, calculators, office machines, etc, this may al-ready result i.n an inadmissibly high angular distortion or twisting of the pushbutton and, above all, of the contact spring 14. If/ in accordance with the invention, ho~ever, the angular fixing is carried out at a point lying radially further towards the outside, it is possible, by maintaining the same tolerance, to achieve an angular accuracy which i5 higher by the factor 2 to 4. By arranging the guide grooves 43 inside the cover 25, the s~itch con-struction can be kept particularly small in the travel cont'd.

R.L.Frlcke 2-10-1-3 direction. The sliding fingers 40, in addition there-to, may serve to restrict the travel of the switch plunger 11 or of the pushbutton key in the upward and /or downward direction.

E~ol~.

4 he~ or~ ~v~h~};

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An electrical pushbutton switch comprising, in combination:
a casing having an axis, axially extending wall portions, a base portion and at least two radially spaced stationary con-tacts mounted to said base and extending axially upwardly;
a rod-shaped switch plunger axially movable in said casing and having a pair of arms extending in radially opposite directions from an axially intermediate portion of said plunger;
a leaf spring contact mounted at a central portion thereof to the axially inner end portion of said plunger and extending outwardly in radially opposite directions therefrom for engaging said stationary con-tacts when said plunger is moved toward said base;
a compression spring extending through a transverse through bore in an intermediate portion of said plunger and respectively terminating in radially opposite groove portions of said wall portions of said casing, said compression spring resiliently urging said plunger away from said base; and, a cover enclosing the axially outer end portion of said casing and having a central opening for receiving said plunger and said cover having a pair of axially extending radially opposite guide grooves for receiving radially outer ends of said arms for guiding and angularly orientating said plunger.
CA000413157A 1981-10-09 1982-10-08 Pushbutton switch, in particular key switch Expired CA1191180A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
DE3140199A DE3140199C2 (en) 1981-10-09 1981-10-09
DEP3140199.6 1981-10-09

Publications (1)

Publication Number Publication Date
CA1191180A true CA1191180A (en) 1985-07-30

Family

ID=6143771

Family Applications (1)

Application Number Title Priority Date Filing Date
CA000413157A Expired CA1191180A (en) 1981-10-09 1982-10-08 Pushbutton switch, in particular key switch

Country Status (5)

Country Link
US (1) US4514609A (en)
EP (1) EP0077011A3 (en)
JP (1) JPS58108618A (en)
CA (1) CA1191180A (en)
DE (1) DE3140199C2 (en)

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0309741A1 (en) * 1987-09-30 1989-04-05 Oerlikon-Contraves AG Push-button electrical switch
FR2629943B1 (en) * 1988-04-06 1994-04-15 Itt Composants Instruments Electric switch with touch effect
US4839475A (en) * 1988-04-29 1989-06-13 Limitorque Corporation Modular switch assembly having wiping contacts
JP2561697Y2 (en) * 1992-08-28 1998-02-04 アプルス株式会社 Lancet
JP3144718B2 (en) * 1992-10-26 2001-03-12 アプルス株式会社 Blood collection device
US5628765A (en) * 1994-11-29 1997-05-13 Apls Co., Ltd. Lancet assembly
EP0783868B1 (en) * 1995-07-28 2003-04-09 Apls Co., Ltd. Assembly for adjusting the piercing depth of a lancet
US6064016A (en) * 1998-08-04 2000-05-16 Itt Manufacturing Enterprises, Inc. Wiper switch terminal and contact
TWM300861U (en) * 2006-03-20 2006-11-11 Hon Hai Prec Ind Co Ltd Slide switch
JP6432487B2 (en) * 2015-11-06 2018-12-05 オムロン株式会社 switch

Family Cites Families (20)

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Publication number Priority date Publication date Assignee Title
US1699645A (en) * 1925-10-29 1929-01-22 Roach Appleton Mfg Company Switch
BE449087A (en) * 1942-02-10
US2661408A (en) * 1946-03-09 1953-12-01 United Carr Fastener Corp Electrical switch
DE1003318B (en) * 1955-04-23 1957-02-28 Maecker Elan Schaltelemente Push switch
US3164708A (en) * 1960-10-27 1965-01-05 Automatic Elect Lab Precious metal tip for strowger switch wipers
US3196230A (en) * 1962-09-19 1965-07-20 Cts Corp Snap action pull-push type electric switch
US3336455A (en) * 1965-05-05 1967-08-15 Square D Co Push button operated switch structure
US3319022A (en) * 1966-05-04 1967-05-09 American Mach & Foundry Snap switch having an integral over-center snap spring blade
US3591747A (en) * 1969-12-29 1971-07-06 Arrow Hart Inc Lever operated switch with tiltable contact actuator and flexible contacts
US3668347A (en) * 1970-01-19 1972-06-06 Robertshaw Controls Co Snap acting electrical switch construction having reset means
DE2022178A1 (en) * 1970-05-06 1971-11-18 Bbc Brown Boveri & Cie Contact arrangement with switching bridge
US3624332A (en) * 1970-09-09 1971-11-30 Oak Electro Netics Corp Snap switch
US3736395A (en) * 1971-02-03 1973-05-29 E Miller Direct-action switch
DE7220520U (en) * 1972-05-31 1974-10-10 Siemens Ag
US3902032A (en) * 1974-06-07 1975-08-26 Illinois Tool Works Electrical switch with improved contact structure
US4006322A (en) * 1975-09-22 1977-02-01 Allis-Chalmers Corporation Auxiliary interlock switch with interchangeable and reversible chisel-shaped contacts and spring biasing mechanism
DE2601206A1 (en) * 1976-01-14 1977-07-21 Priesemuth W Motor vehicle brake lamp switch - has two opposite contact blades with guideways in housing for U:shaped switching contact
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Also Published As

Publication number Publication date
DE3140199C2 (en) 1984-03-22
CA1191180A1 (en)
JPS58108618A (en) 1983-06-28
EP0077011A3 (en) 1985-05-15
EP0077011A2 (en) 1983-04-20
US4514609A (en) 1985-04-30
DE3140199A1 (en) 1983-04-28

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Legal Events

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